Power transmission line is an important part of power system, it is the artery of electric power system. However, long distance transmission wires are basically exposed to the outside, which is vulnerable to be affected by climate, geology and human factors. The pollution flashover, lightning stroke, wire icing and galloping caused huge losses to power grid. Operation states of power transmission line directly determines safety and efficiency of power system.
It is of great significance for realizing intelligent power transmission to monitor operation states of power transmission wire. At present, short distance wireless communication technology is an important supporting technology for power transmission line status monitoring. Among them, ZigBee technology and Bluetooth 4 technology have been rapidly developed in recent years, which has a positive effect on power transmission line status monitoring.
ZigBee technology is a new generation of wireless communication technology developed by IEEE. This technique is mainly aimed at low rate sensor network, which can meet miniaturization and low cost requirements of wireless network. Due to advantages of low power consumption, low cost, large capacity, short delay, self-organizing ability, data security and so on, ZigBee technology has been widely used in many fields, such as medical care, security alarm, wireless ordering, water conservancy monitoring, oil field measurement and control, electric power measurement and control.
Traditional Bluetooth technology is affected by transmission distance, power consumption and other factors, so application of this technology is limited. This status was change by appearance of Bluetooth Technology 4.0. Bluetooth 4.0 has very low operation and standby power consumption, which can make a button battery continuous work for several years. In addition, low cost and cross vendor interoperability, adaptive frequency hopping, 1 Mbps data transfer rate, 3 ms low latency, more than 100 meters long distance, AES-128 encryption and many other features, so Bluetooth 4.0 can be used in many fields, such as pedometer, heart rate monitor, intelligent instrument, internet of things. These fields greatly expand the scope of Bluetooth Technology application.
According to applicant's knowledge:
(1) ZigBee technology also has limitations, such as application of this technology is limited due to low data transmission rate. Although direct sequence spread spectrum technology is used to reduce the loss, this method is lack of ability to resist interference. In addition, the 2.4 GHz band provides less working channel and is easy to cause interference and conflict between nodes.
(2) Compared with ZigBee Technology, Bluetooth 4.0 technology also has its own limitations, such as support less topology structure, single network mode, unsupported mesh networking, low robustness and less accommodating node.
Moreover, energy consumption is one of the main factors that restrict short distance wireless communication technology. Research shows that energy consumption of short distance wireless communication mainly includes two parts: one part is node power consumption that can be solved by using low power nodes. Another part, the biggest part of energy consumption is the energy consumption when node sends and receives data.
Under this background, a lot of energy balancing routing protocols are proposed. Energy consumption of each node can be guaranteed by clustering method to prevent nodes from energy exhaust and stop working due to forwarding data too much. However, the idea of clustering is not suitable for monitoring status data of power transmission line.
Mainly reflected on: (1) there are a limited number of monitoring nodes between each tower, and monitoring nodes are in accordance with Zonal distribution, the method of clustering has little significance. (2) method of clustering is used to divide nodes that monitoring the same object more than others into clusters. However, few nodes monitor the same object along one power transmission line and distribution of nodes is more dispersed, which is not suitable for clustering. Belt monitoring scene of power transmission line determines that the farther away from sink node, the less forwarding times and the less energy consumed. Nodes that the closer to sink node, the more energy consumed by forwarding too much, which leads to these nodes stop working because of energy exhaustion.
At the same time, it is easy to receive multiple forwarding requests in one data forwarding process and trigger forwarding conflict, which cannot guarantee the quality of data transmission and cause low data transmission rate.
Therefore, a forwarding node selection mechanism suitable for monitoring status data of power transmission line is proposed, it is of great significance to balance energy consumption of nodes and prolong service life of the whole network.